Cover a sheet pan with foil or parchment. Preheat oven to 400°
Slice the eggplant long-wise in ½-inch slices. You should get about 8 slices. Place on the sheet pan and brush both sides with olive oil. Season with salt and pepper and bake for 30 minutes. Leave the roasted slices on the pan.
While the eggplant is roasting, stir together ricotta, lemon juice and season to taste with salt and pepper. Once the cheese is seasoned, stir in the egg.
Top half of the roasted eggplant slices with ricotta. Put the other half of the slices on top of the ricotta, stacking it like a sandwich. Divide the marinara among the stacks, top the marinara with mozzarella, and sprinkle parmesan on top. Put the sheet pan back in the oven for 5 or 10 minutes until the mozzarella is melted and the eggplant parmesan is hot.